It comforts you to look at your team and see 2-2-2. Seeing 5 people lock dps gave you anxiety or pissed you off so you already have the mentality that you’re going to lose going into the game.
I’ve been playing since season 2 and the truth is 5 dps games were VERY rare back then anywhere above bronze. This was back when Dva Winston were the best tanks and people loved playing them so getting a balanced team was quite common. This was ruined by the release of Brigitte. Brig was so stupidly broken, launched as the best tank healer and dps in the game and so people got frustrated. They stopped caring about team comps and just wanted to blast Brigitte to hell, thus the sub reddit /r/watchbrigittedie was born (it was fabulous) and high dps team comps became more common.
Brig was a major negative turning point in overwatch both for the game and the community.
Some brig nerfs later, a few months before role lock was introduced, 5 dps comps were more common than pre brig but they were still rare. Yes they would happen sometimes but here’s where I want to talk about how even the 5 dps games people like to complain about when they justify role queue, were more winnable than a FAR more common situation we get now in role lock which is the 2 tanks that unbound their W key and expect dps to kill everything when they stand in one spot holding a shield.
Open queue allowed people to switch to compensate for an underperforming role. You can’t do this in role lock and when you’re stuck with 2 trash tanks which is very common, you have about a 5% chance of winning. Open queue games with 5 dps, yes they’re not easy to win but honestly they’re FAR more winnable than the former, and they always have a chance to not be 5 dps as the game progresses.
A couple months before role lock was released, I remember changing my attitude about seeing 5 dps comps from “OMG GG” to “you know what, let’s utilize health packs, use soldiers heal, communicate and let’s win” and I won several SIX dps games from shot calling and bringing team work to a “troll” comp and damn they were fun. High dps comps were never actually bad as long as people could play their heroes, it was just high risk high reward; the ultimate glass cannon. People who played comp before role lock know its true, there were times your team got stomped by all dps comps. If you lost every game you had 5 dps you just needed to change your attitude.
In conclusion, I believe open queue should return to being the main comp mode in OW2 because it allowed for much more exiting and dynamic gameplay, it allowed players to play their strengths, it had less throwers because people didn’t just care about one of their roles SR, and it provided more opportunities for players to change the direction of a game by switching to the role that is underperforming. Byyyyyeeeee 
love ya